This invention relates to the conversion of a tertiary amine to corresponding primary and secondary amines. More particularly, it relates to such conversion of a trialkanolamine by reaction with ammonia.
It is known that trialkylamines can be converted to the primary and secondary amines and secondary amines can be converted to primary amines by reaction with ammonia at moderately elevated temperatures, in the presence of a hydrogenation catalyst. Such processes are described by Millington, U.S. Pat. Nos. 2,112,970 and by Olin et al., 2,192,523. It is also known that amines containing hydroxyl groups such as monoalkanolamines and dialkanolamines react with ammonia under similar conditions to produce polyamino compounds or heterocyclic nitrogen compounds, for example, ethylenediamine, N-aminoethylethanolamine, piperazine, and related compounds, depending upon the starting material and the conditions of reaction. Processes of this kind are disclosed by MacKenzie, U.S. Pat. Nos. 2,861,995, Long 2,910,477, and Fowler, 2,519,560.
In the preparation of lower alkanolamines such as ethanolamine, isopropanolamine, and butanolamine by the reaction of an alkylene oxide with ammonia, substantial quantities of the corresponding secondary and tertiary amines are also produced, the proportions of these products depending upon the ratio of reactants used and other process conditions. However, product distribution cannot always be modified enough by the ratio of reactants to meet sales demands. When the reaction mixture is distilled to separate the various products, substantial quantities of the trialkanolamine product remain as still bottoms, the trialkanolamine content of these residues usually running about 80 to 90 percent. Although these still bottoms have some useful properties when used as such with little further treatment, it would be advantageous to be able to convert this material to other useful products and thus vary the product mix obtainable from an alkanolamine process. This invention provides an additional way to modify the product distribution by converting a lower trialkanolamine to the corresponding monoalkanolamine and dialkanolamine.